Auto-calibrating tyre pressure monitoring system

Abstract

Methods and apparatus for fitting to a wheel of a vehicle comprising a pneumatic tyre, the sensor module comprising: a pressure sensor for sensing pressure of a gas retained within the pneumatic tyre; an alert generator configured to generate one or more alert signals based on the sensed pressure of the gas and a calibrated tyre pressure; and a controller configured to receive pressure data from the pressure sensor and determine whether the tyre is being inflated or deflated by a user, and subsequently re-set the calibrated tyre pressure to the pressure of the gas after inflation or deflation.

1 . A tyre pressure sensor module for fitting to a wheel of a vehicle comprising a pneumatic tyre, the sensor module comprising:
 a pressure sensor for sensing pressure of a gas retained within the pneumatic tyre;   a motion sensor;   an alert generator configured to generate one or more alert signals based on the sensed pressure of the gas and a calibrated tyre pressure; and   a controller configured to receive pressure data from the pressure sensor and motion data from the motion sensor and determine whether the tyre is being inflated or deflated by a user based on the pressure data and the motion data, and subsequently re-set the calibrated tyre pressure to the pressure of the gas after inflation or deflation.   
     
     
         2 . The tyre pressure sensor module according to  claim 1 , wherein the pressure sensor is positioned rearward of a valve inlet of the tyre. 
     
     
         3 . The tyre pressure sensor module according to  claim 1 , wherein the controller is configured to receive the pressure data periodically. 
     
     
         4 . The tyre pressure sensor module according to  claim 3 , wherein the controller is configured to receive the pressure data at a first frequency in a default mode, and to receive the pressure data at a second frequency greater than the first frequency in a monitoring mode. 
     
     
         5 . The tyre pressure sensor module according to  claim 1 , wherein the controller is configured to determine that the tyre is being inflated or deflated in dependence on the pressure of the gas changing at a rate higher than a threshold. 
     
     
         6 . The tyre pressure sensor module according to  claim 1 , wherein the controller is configured to determine that the tyre is being inflated or deflated in dependence on the motion data indicating that the sensing module is stationary. 
     
     
         7 . The tyre pressure sensor module according to  claim 5 , wherein the controller is configured to monitor an increase in the pressure of the gas after the threshold is reached, and is further configured to re-set the calibrated pressure after the pressure of the gas has stabilised. 
     
     
         8 . The tyre pressure sensor module of  claim 5 , wherein the controller is configured to monitor a decrease in the pressure of the gas after the threshold is reached, and is further configured to re-set the calibrated pressure after the pressure of the gas has stabilised. 
     
     
         9 . The tyre pressure sensor module of  claim 1 , wherein the controller is further configured to re-set the calibrated pressure after the pressure of the gas has stabilised for a predetermined period of time. 
     
     
         10 . The tyre pressure sensor module of  claim 7 , wherein if the pressure of the gas has not stabilised after a threshold time, the calibration pressure is not re-set. 
     
     
         11 . The tyre pressure sensor module of  claim 4 , wherein if the pressure of the gas has not stabilised after a threshold time, the controller is configured to enter the default mode. 
     
     
         12 . A tyre pressure monitoring system comprising:
 a plurality of tyre pressure sensing modules according to  claim 1 ; and   a driver indicator unit.   
     
     
         13 . A vehicle comprising a tyre pressure monitoring system according to  claim 12 . 
     
     
         14 . A method for re-setting a calibrated tyre pressure of a tyre pressure sensor module comprising a pressure sensor and a motion sensor and fitted to a wheel comprising a pneumatic tyre, the method comprising:
 sensing a pressure of a gas retained within the pneumatic tyre;   obtaining motion data from the motion sensor;   generating one or more alert signals based on the sensed pressure of the gas and a calibrated tyre pressure; and   receiving pressure data from the pressure sensor and motion data from the motion sensor and determining whether the tyre is being inflated or deflated by a user based on the pressure data and the motion data, and subsequently re-setting the calibrated tyre pressure to the pressure of the gas after inflation or deflation.   
     
     
         15 . A non-transitory computer-readable medium having stored there upon a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to control an apparatus to carry out a method according to  claim 14 . 
     
     
         16 . The method of  claim 14 , wherein determining whether the tyre is being inflated or deflated is in dependence on the pressure of the gas changing at a rate higher than a threshold. 
     
     
         17 . The method of  claim 14 , wherein determining whether the tyre is being inflated or deflated is in dependence on the motion data indicating that the sensing module is stationary. 
     
     
         18 . The method of  claim 14 , further comprising:
 monitoring an increase in the pressure of the gas after the threshold is reached, and re-setting the calibrated pressure after the pressure of the gas has stabilised.   
     
     
         19 . The method of  claim 14 , further comprising:
 monitoring a decrease in the pressure of the gas after the threshold is reached, and   re-setting the calibrated pressure after the pressure of the gas has stabilised.   
     
     
         20 . A sensor module comprising:
 a pressure sensor configured to sense a pressure of a gas retained within a pneumatic tyre;   a motion sensor;   an alert generator configured to generate one or more alert signals based on the sensed pressure of the gas and a calibrated tyre pressure; and   a controller configured to:
 receive pressure data from the pressure sensor, 
 receive motion data from the motion sensor, 
 determine whether the tyre is being at least one of inflated or deflated in dependence on the motion data indicating that the sensing module is stationary, and 
 re-set the calibrated tyre pressure to the pressure of the gas after inflation or deflation.